Deathlords were once part of the paladin order. When Arthas took up the sword against his own people in Stratholme, the deathlords committed the same heinous act in many other cities across Lordaeron. The act of evil must have been so great that the evil transformed them into revenants, and they scattered to different parts in the world, haunting the regions they once walked on with human legs. Eldritch Deathlord turned from the Light when he slaughtered his own family, believing they were impure, therefore making himself an evil and banished outlaw.